1.代码：
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>01triangle</title>
<style>
.box {
width: 0px;
height: 0px;
/* background-color: red; */
border: 50px solid transparent;
border-left: 50px solid rgb(255, 174, 0)
}
</style>
</head>
<body>
<div class="box">
</div>
</body>
</html>2.效果图
